The present invention relates in general to a solidstate timing circuit, and pertains, more particularly, to a timer circuit for a vending machine which may be programmed to operate on different coinage values and which further can be programmed to operate a vending machine through different length vending periods. In the disclosed embodiment of the present invention the machine may be operated on coinage of 5 cent or 10 cent denomination up to a total of 75 cents. The vend period is also settable and usually on the order of seconds.
One object of the present invention is to provide an improved timer circuit for a vending machine. The circuit of this invention is preferably for vending machine that vends a liquid such as a soda or fruit juice.
Another object of the present invention is to provide an improved timer circuit for a vending machine that is essentially tamper-proof. In some known circuitry the vending period can be initiated by interrupting power to the machine. However, in accordance with the present invention this circuitry is adapted to prevent any operation of the vending machine by selective temporary power interruption.
Still another object of the present invention is to provide an improved timer circuit for a vending machine that is easily adapted for use with either 110 VAC or 220 VAC input power.
A further object of the present invention is to provide an improved timer circuit preferably for a vending machine and which is of relatively simple construction requiring a minimum number of components and which can be made quite inexpensively.
To accomplish the foregoing and other objects of this invention there is provided a circuit that includes a counter having first and second counter sections (fields) with one section corresponding to coinage necessary to initiate the vend period and the other section associated with the time of termination of the vend period which of course relates to the length thereof. The counter is preferably a binary counter having an input means usually in the form of a clock input for incrementing the counter and output lines usually a plurality being associated with each section of the binary counter. The counter is counted through a first phase until a count is received corresponding to the proper coinage and thereafter the counter is continuously clocked until a second count is received through a second phase of operation representative of the vend period.
In addition to the counter, the circuit of this invention also comprises an input coinage circuit responsive to the insertion of coinage into the machine for generating a signal coupled to the counter for incrementing the counter. In the disclosed embodiment both 5 cent and 10 cent pieces operate the counter with the insertion of each 5 cent piece creating one pulse and the insertion of each 10 cent piece generating two pulses to increment the counter. The output of the circuit of this invention may comprise a circuit means such as a triac for operating a load during the vend period. The load may typically be a motor for operating an auger for dispensing a drink powder. The load usually also includes a solenoid for operating the water associated with the drink. A first settable decoder means couples from the output lines of the first section of the counter for providing a signal for initiating the vend period of the circuit means. Also, there is provided a second settable decoder means coupled from output lines of the second section of the counter for providing a signal terminating the vend period of the circuit means. Both settable decoder means comprise a switch array that is preset with one portion of the array preset for the coinage and the other portion preset for defining the duration of the vend period. The circuit of this invention preferably also includes a power supply, reset circuitry, and circuitry for preventing erroneous operation of the vending machine.